Exploratory Evaluation of Refractometric, Biochemical, and Body Weight Change Parameters for Diagnosing Failure of...

Failure of passive transfer (FPT) is an important determinant of survival in neonatal puppies. Practical indirect indicators that could serve as alternatives to measuring serum immunoglobulin G (IgG) have not yet been adequately characterized. In this exploratory study, 76 Turkish Kangal puppies aged 48 ± 4 h, born to 12 dams (mean age 40.2 months) were evaluated. Serum IgG measured by ELISA was the reference method, with values below 2.3 g/L classified as FPT. Whole-blood, fresh-serum, and frozen-thawed serum Brix values were evaluated together with serum total protein, albumin, globulin, gamma-glutamyl transferase, canine parvovirus antibody levels, and percentage change in body weight from birth to sampling, using receiver operating characteristic analysis. FPT was identified in six puppies (7.9%). The area under the curve (AUC) values for total protein, globulin, and percentage change in body weight were 0.986, 0.981, and 0.948, respectively, with the associated cutoffs considered exploratory; each detected all six cases with 82.9-94.3% specificity. Fresh-serum Brix showed moderate discrimination (AUC: 0.771), whereas whole-blood Brix was inconclusive (AUC: 0.432). Total protein, globulin, and early body weight change are promising screening indicators for detecting FPT. However, because of the limited number of cases, their cutoffs should be validated in larger populations, including other breeds, before clinical use.